<!DOCTYPE html>
<script>
    onload = function() {
        var elm = document.getElementById('elm');
        elm.offsetTop; // trigger layout
        elm.style.WebkitColumns = '6';
    }
</script>
<p>There should be nothing below.</p>
<div id="elm" style="-webkit-column-gap:0; width:4em; overflow:hidden;">
    <div style="-webkit-column-span:all; padding-left:4em;">
        <!-- column-span:all inside column-span:all has no effect. -->
        <div style="-webkit-column-span:all;">
            FAIL
        </div>
    </div>
</div>
